The present invention relates to a contact element in the form of a spring contact jack or spring plug pin, with a plurality of mutually laterally disposed spring contacts which can be attached at one end to a support piece and which are radially curved in order to provide contact with an opposing contact; and the invention further relates to a method of manufacturing said contact element.
It is known from German OS No. 25 58 003 to employ, in manufacturing spring contact jacks, a spring contact mat comprised of spring contact wire curved in a meander shape or "wave shape". In this contact spring mat the segments of contact spring wire, which run parallel to each other, are connected by arcuate segments. This configuration has turned out to be disadvantageous in that there is a practical lower limit to the radius of curvature, and thereby a lower limit to the separation of the contact spring wire segments. Wholly apart from the fact that said mat is difficult to manipulate due to its unavoidable expandability, it has proven disadvantageous that the arcuate segments resist bending around an axis parallel to the spring contact wire segments. Thus, in order to bend the mat into a permanent cylindrical shape, it is necessary to distort the spring contact wire segments; and further it is not practically possible to predict the degree of such distortion. Thus, spring contact jacks with meander-shaped pre-formed spring contact wire have not proven feasible in practice, particularly not in miniature applications.
In manufacturing spring contact jacks having small dimensions (German Pat. No. 3,342,742 and U.S. Pat. No. 4,572,606 corresponding thereto) one also employs spring contact wire segments which are individually mounted in a jack body. The prefabricated tubes which serve as the jack bodies are manufactured efficiently by drawing. They have wall thickness on the order of 0.1 mm and are easily deformed from outside. After the contact springs are inserted, the jacks are each provided with a radially inwardly extending, ring-shaped ridge-like projection or bead, at each of two axially separated loci (axially with respect to the ring-shaped body or ring-shaped shoulder or the like). The ring-shaped ridge-like projections come to abut the spring contacts and cause said springs to curve radially inward.
In the manufacture of a spring contact jack of a different structure (U.S. Pat. No. 3,023,789), wherein individual contact springs are employed, spring contacts are disposed along peripheral lines of a hyperboloid of rotation, in a rigid sleeve, and their bent-around ends are pressed against the end of the sleeve. Contact spring jacks manufactured according to this method do in fact enable the desired miniaturization. However, they have the following drawbacks:
the spring ends cannot be galvanically anodized or otherwise galvanically finished;
very strict tolerances are imposed between the plug and the jack, particularly in light of the unfavorable spring characteristic curve; and
only relatively few spring contacts can be installed, whereby the current passed will thus be limited.